A stock restore to 4.3.1 can be done if it was done a couple of days after 4.3.2 is released, after the 2 days grace period (if you are lucky) then it will not be possible to restore to 4.3.1 UNLESS you have saved your SHSHs via TinyUmbrella. After the grace period of a couple of days (or less), then Apple will stop signing the 4.3.1 firmware (which I assumed Apple has done just that) and any effort to try and restore to 4.3.1 will be met with a 3194 error (if you are using a Windows PC) or an "Ineligible Firmware Build" error (if you are using a Mac)

The only way to restore to 4.3.1 (or anything lower) will be via the TSS Server or Cydia Method. This method requires you to have SAVED the 4.3.1. SHSHs blobs during the period where Apple was still signing it (i.e. before Apple update 4.3.1 to 4.3.2)

I can elaborate on the TSS server/Cydia method further if anyone requests it but lesson learned is that

1. ALWAYS backup your SHSHs blobs .... YOU DO NOT NEED TO JAILBREAK your iPhone to backup the SHSHs. You just need TinyUmbrella (Google for it) and you can save the SHSHs blobs either to Cydia or to your local machine (I prefer this method).